Epithelial injury induces egr-1 and fos expression by a pathway involving protein kinase C and ERK

Am J Physiol. 1999 Feb;276(2):G322-30. doi: 10.1152/ajpgi.1999.276.2.G322.

Abstract

The signaling pathways activated in response to gastrointestinal injury remain poorly understood. Previous work has implicated the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase as a mediator of wound-signal transduction and a possible regulator of epithelial restitution. Monolayer injury resulted in rapid activation of p42 and p44 ERK. Injury-induced ERK activation was blocked by protein kinase C inhibition or by disruption of the cell cytoskeleton. Significant increases in Fos and early growth response (Egr)-1 mRNA levels were stimulated by injury, peaking by 20 min. ERK activation and the induction of Egr-1 mRNA were inhibited in a dose-dependent fashion with PD-98059. Fos mRNA expression was partially blocked by PD-98059. Western blot analysis demonstrated strong expression and nuclear localization of Fos and Egr after wounding. Electrophoretic mobility shift assays demonstrated that nuclear extracts contained a protein that specifically bound double-stranded oligonucleotides containing the Egr consensus binding element. Gel supershift assays demonstrated that the protein-DNA complexes were recognized by anti-Egr antibody. Inhibition of injury-induced ERK activation by PD-98059 or direct interference with Egr by expression of a dominant negative mutant led to significantly reduced in vitro monolayer restitution.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Cell Line
  • Cell Nucleus / metabolism
  • Consensus Sequence / genetics
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Duodenum / injuries*
  • Duodenum / pathology
  • Early Growth Response Protein 1
  • Enzyme Activation / drug effects
  • Enzyme Activation / physiology
  • Enzyme Inhibitors / pharmacology
  • Epithelial Cells / metabolism
  • Immediate-Early Proteins*
  • Nuclear Proteins / metabolism
  • Oligonucleotides / chemistry
  • Oligonucleotides / metabolism
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism*
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism*
  • RNA, Messenger / antagonists & inhibitors
  • Rats
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Wounds, Penetrating / metabolism*

Substances

  • DNA-Binding Proteins
  • Early Growth Response Protein 1
  • Egr1 protein, rat
  • Enzyme Inhibitors
  • Immediate-Early Proteins
  • Nuclear Proteins
  • Oligonucleotides
  • Proto-Oncogene Proteins c-fos
  • RNA, Messenger
  • Transcription Factors
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinases